Hadhrat Sirri Saqati رحمة الله عليه has mentioned: استغفارنا يحتاج إلى استغفار كثير (Our istighfaar (seeking of repentance) is in need of abundant istighfaar). This is because our istighfaar is a mere lip service and it is not done sincerely. Thus, it amounts to mockery of Allah Ta`ala.

It is similar to the case of where a person beats another and then asks for forgiveness insincerely without any remorse for his doings. (He is not asking for forgiveness but rather mocking the person.)